Ar-15 extraction problems and failure to lock back after last round

[October]

So before I modified anything with this gun I noticed the bolt started not locking back after the last round was fired. I was planning on re-doing some of the gun the next day so I did anyways and put this issue aside. I replaced the A2 FSB with a rail height gas block, got a new gas tube, some new furniture and took her for a spin.

First few shots went off fine then I started getting failure to extracts. It was ripping the rim of the brass upwards and leaving it in the barrel. Went home, posted about it, found some help and methods to check that my gas system was alright. Gas flow seemed sufficient so I decided to get a BCM extractor kit just to see if that helped at all. Took it out today and had the same problem but not as frequent. And i noticed that it only did it with this particular ammo I just bought 200 rounds of. It didnt do it with the Tulammo or the federal at all. They all extracted fine.

But I was still getting a failure to lock back after the last round. ONE time it locked back and that was it. And it didnt matter which mag I used. But it does lock back fine if I do it by hand, slow and fast. Just got home, and took out my spring, it measures 11 inches, everything looked normal on it. Not sure where to go from here.

Magpul PMAG
C-Products 10/20 round mag
JD Machine Upper
JD Machine Lower
Citadel 16" barrel
Rock River BCG w/ BCM Ext kit

EDIT: Oh and I just started using 5.56. I have always shot .223 no problem. I started getting the no lock back when I used 5.56. Any reason to that?

[problemchild]

We need an AR-15 problem solving flowchart. Its the same issues week after week.

[October]

We need an AR-15 problem solving flowchart. Its the same issues week after week.

ya that would be nice. But for now, its a forum full of people that chime in with help, even if they just helped someone with the same problem. Almost every thread I have researched regarding this issue had no conclusion

[el tardo]

so not locking back is to little gas(most of the time) and you said you tried different ammo as well. if you have a H2 buffer you can try a lighter buffer to make it work(maybe).
you said you put a new gas block,it its not centered you dont get all your gas flow.
im just guessing cause i dont have the gun in front of me.
im guessing you did the normal things like lube it very well.

now your ejecting problem could be many things(easiest first)and happened to me once, clean out the chamber very well. i was shooting steel case and the lacquer started to build up and made it hard for the shells to eject,even brass. the throat gets hot and turns the lacquer to glue basicly and binds the shell.
if thats not it , its up to you cause im not typing a whole book,sorry.

[Germz]

why don't we start with you telling us what ammo you are using?

[October]

why don't we start with you telling us what ammo you are using?

The ammo that had extraction problems:

http://www.freedommunitions.com/5-56-M-193-55-gr-FMJ-New-p/ipp556m193n-b0200.htm

Ammo that didn't have issues:

Tulammo .223 and I can't remember the exact name of the other one but it was federal 5.56 M-1(something) ball. Brown boxes at Walmart for 11 bucks.

so not locking back is to little gas(most of the time) and you said you tried different ammo as well. if you have a H2 buffer you can try a lighter buffer to make it work(maybe).
you said you put a new gas block,it its not centered you dont get all your gas flow.
im just guessing cause i dont have the gun in front of me.
im guessing you did the normal things like lube it very well.

now your ejecting problem could be many things(easiest first)and happened to me once, clean out the chamber very well. i was shooting steel case and the lacquer started to build up and made it hard for the shells to eject,even brass. the throat gets hot and turns the lacquer to glue basicly and binds the shell.
if thats not it , its up to you cause im not typing a whole book,sorry.

but I started having the non lock back problem before i changed anything on the gun. When i first got the gun I only shot american eagle .223. Never had an issue of non-lock back. Then I started using federal 5.56 and started getting non lock back. And now extraction problems on the linked ammo abaove

[el tardo]

im sticking with my answer, you need a good gun cleaning, to clean the throat you need a nylon brush on a drill with some clp and then come back and tell us if it does the same thing.when doing this after lacquer ammo(steel) you'll see alot of black crap come out of the throat.the throat should look like chrome.not dark and black.
tula 223 ammo has less power then 556,so if it worked and 556 didnt it not gas.
sounds to me to be to much drag (cause its dirty) and thats whats causing your ejection problem too.

[Dhena81]

OP your all over the place. Your saying your gun worked at first with American eagle but at the same time you were having issues locking back before you switched parts.

Then your gun continued having issues but not when you shot Tula or Federal 193.

Now your gun has issues extracting the 5.56 freedom munitions ripping case rims. (probably a timing issue)


I'd start from the beginning did you ever have issues feeding rounds or only bolt hold open?

[October]

im sticking with my answer, you need a good gun cleaning, to clean the throat you need a nylon brush on a drill with some clp and then come back and tell us if it does the same thing.when doing this after lacquer ammo(steel) you'll see alot of black crap come out of the throat.the throat should look like chrome.not dark and black.
tula 223 ammo has less power then 556,so if it worked and 556 didnt it not gas.
sounds to me to be to much drag (cause its dirty) and thats whats causing your ejection problem too.

i only sued steel cased once before and it was about 60 rounds. Have only about 500 rounds through this rifle and its all been brass.

Should I try getting an H-buffer to see if that fixes the lock back issue? And i dont think its because its dirty. Why would two different brands of ammo work perfect (minus not locking back after last shot) but one brand foul out every 1 out of 20 times? Ill clean it anyways though with a nylon brush and drill to see

[el tardo]

i only sued steel cased once before and it was about 60 rounds. Have only about 500 rounds through this rifle and its all been brass.

Should I try getting an H-buffer to see if that fixes the lock back issue? And i dont think its because its dirty. Why would two different brands of ammo work perfect (minus not locking back after last shot) but one brand foul out every 1 out of 20 times? Ill clean it anyways though with a nylon brush and drill to see

get a flash light right now and look down the throat!! is it polished looking or dirty? that will answer your question in one minute.if it doesnt look polished i would clean it.you need to rule one thing out at a time.

[SimonBirch]

A good ol marine corps cleaning and lubrication will do the trick.

[October]

OP your all over the place. Your saying your gun worked at first with American eagle but at the same time you were having issues locking back before you switched parts.

Then your gun continued having issues but not when you shot Tula or Federal 193.

Now your gun has issues extracting the 5.56 freedom munitions ripping case rims. (probably a timing issue)


I'd start from the beginning did you ever have issues feeding rounds or only bolt hold open?

I never had any issues in the past. I always used .223 American Eagle. Then I decided, after finding out my barrel was rated for 5.56 (i didnt know because there are no markings on it at all), to buy some 5.56 which was the federal 193. WHen I took that out, it fired and extracted perfectly fine but the bolt would never lock back after the last round. THEN, I ended up revamping my gun and putting a new gas block on it, new gas tube and some furniture.

Took it out with just the 5.56 from munitions freedom and started getting FTE constantly as well as no lock back. Came home, made sure my gas ports were aligned properly, broke everything down and cleaned the heck out of it, including the bolt, and then installed the BCM extractor kit (minus the 0-rings).

Took it out today with 3 types of ammo. 5.56 M193 federal, 5.56 freedom munitions and .223 Tulammo.

Federal had no extraction problems but wouldnt lock back after last shot.
Tulammo had no extraction problems and did lock back (the one time, only used one mag of it since I hate steel cased)
Freedom munition 5.56 had a handful of FTE and the bolt did not lock back after final shot.

get a flash light right now and look down the throat!! is it polished looking or dirty? that will answer your question in one minute.if it doesnt look polished i would clean it.you need to rule one thing out at a time.

Well i just went through about 150 rounds, wont it look dirty?

[el tardo]

why are you fighting us? you came here for help,we didnt come to you??
dont take it personal and just do what we ask please.

[SB1964]

I would start by cleaning the chamber with a proper chamber brush & the barrel. Make sure you have a good quality standard weight buffer spring & I'd start off with an "H" buffer, not an H2. If you're not sure what kinda spring you have, get another one, they are cheap, just get quality. As you get it working correctly, KEEP the standard weight buffer spring & if you want to, use heavier buffers as needed. Take apart the Bolt carrier group (BCG) & have a good look at the bolt face. Use a brass brush & scrub the edges of the extractor, get underneath the edge too. Look carefully at it, chipped? worn or funny looking edges? If the extractor looks solid & the spring on it's FIRM, lube it generously & re=assemble. The spring should be firm, but pivot. Make sure the buffer tube is assembled/mounted correctly & CLEAN also, either dry, or wipe a light film of CLP AT THE MOST. I've heard of & seen guys grease the tube. The gas system, ammo, bolt catch & magazines ALL affect bolt locking.

[October]

why are you fighting us? you came here for help,we didnt come to you??
dont take it personal and just do what we ask please.

Im confused what I'm fighting about or taking personally...? I was answering the questions asked????

And I was saying that since I just shot 150 rounds won't it look dirty? And there's a bit of brass fragments now from all the FTE today. But even when I took a brass brush then nylon brush to it it still wasn't chrome.

Still confused how you think im fighting with anyone or what I took personally